Fuel vaporizer for jet propulsion units



Oct. 2, 1945. K. K. NAHIGYAN 2,385,333

' FUEL VAPORIZER FOR JET PROPULSION UNITS I Filed Jan. 27, 1943 INVENTOR for burning liquid fuels rapidly rateiaeiioctzlm UNI'IED- STATES PATENT Oi FlCE p 2,385,833 j mu VAPORIZEB FOB 1m PROPULSION,

Kevork x. Nahigyan, Hampton. Va. Application January 21, 194:, Serial No. 413.105 9 Claims. (01. se -ss),

(Granted under the act of March amended April 30, 1928; 370 0.

This invention relates in general to jet propuision motors and in particular to an improved construction for a fuel vaporizer used in the combustion duct thereof.

In jet propulsion motors or the class described,

air is inducted at a relatively high, velocitythrough a suitable opening at the forward part of the motor either by forward motion of the aircraft or other vehicle upon which the motor is or augmented by a suitable power driven blower. The air stream thus inducted is heated by the burning of fuel issuing from a vaporizer situated in the path of the air stream through v themotor to further increase its velocity and then rearwardly of the motor to thereby impart a forward thrust to the vehicle.

The velocity of the air column moving through the combustion duct of a jet-propulsion motor is extremely high as compared to the air velocities through other known devices utilizing fuel vaporisers. The performance of jet-propulsion systems in aircraft use is sensitive to the drag im- -.p0sed on the air stream by the vaporizers. Furthermore, the emciency of a jet-propulsion motor depends largely on the completeness of the fuel combustion within the limited space ordinarily available in an eflicient aircraft installation. The weight of the vaporizer is'also sideration in an aircraft installation.

The aforesaid reason for a limited combustion space necessitates extremely high heat liberation. It is important, therefore, to burn the fuel with a non-luminous flame in order to minimize the radiant heat transferred to the walls of the combustion chamber from a given temperature flame.

In summation, the requirements of a fuel vaporizer suitable for aircraft jet-propulsion motors are that it eifect the burning of the fuel efflciently and rapidly with a non-luminous flame in high-velocity air streams, that it be compact and light in construction, and .of such profile that it imposes a negligible drag on the air stream.

The general object of this invention therefore to provide an improved fuel vaporizing device and efliciently in the relatively high velocity air stream. flowing through the air duct of a jet propulsion motor.

A further object of this invention is to provide a fuel vaporizing device which will produce a high temperature flame which has a minimum of radiant heat for the given flame temperature.

"Such a device has particular application to services where a minimum of heattransfer from the 2 shown partly in cross of primary con- 99 flame to the surrounding walls of a chamber are desired.

Another object of this invention is to provide an improved fuel vaporizing device of light construction, and with a profile with thedirection oftheairflowtoimposea of drag onthe air stream.

Still a further object vof this invent-im is to provide an improved device which is simple and economical to construct, maintain, and dependable in prolonged service.

With the foregoing and other objects in View; as will hereinafter become apparent, this invention comprises the constructions, ns, and arrangements of parts, set forth disclosed and shown on the accompanying drawins, wherein;

Fig. 1 is a longitudinal view of a link-unit burner shown partly in cross secflon;

Fig. 2 is a cross-sectional end view taken at line 22 of Fig. 1;

Fig. 3 is a longitudinal view of a in the construction of the vaporizing section;

Fig. 4 is a longitudinal view of a further modification in the construction of the vaporizing chamber;

V Fig. 5 isa cross-sectional end view taken'at line 5-5 of Fig. 4;

Fig. 6 is an end view of the t of a multiplicity of vaporizers in a duct; and

Fig. '7 is an elevational view taken at crosssection line 1-1 in Fig. 6 of an t of a multiplicity of vaporizers.

Figuresl and 2 show one i; of my invention comprising a chamber formed of two hollow cones l and 2 made of a. suita'bhe sheet metal and fastened base to base by joining flanges 3 and 4 provided at bases of cones l and 2, respectively.- The joining of the flanges 3 and 4 may be done by welding, by bolting, or

by any other acceptable method to form a substantially gas-tight joint. Gone I is provided with a collar 5 shown threaded, but which may be constructed otherwise to clamp over the barrel 6 of a fuel atomizing nozzle 1-. In the wall of the cone 2 constituting the after-part of the vaporizing chamber a multiplicity of orifices I are drilled in suitable size and numbers on a circumference at a proper distance 1- of the flange 4.

The vaporizer chamber duct 9 through the body of a jet Pmpulslm motor so that the longitudinal-axis of the vaporizer falls approximately on the l easytoopemteandto' isinstalledinanairaxis of the duct or runs approximately parallel to it. A spark plug it! inserted through the wall of the air duct provides a convenient means for linitially lighting the burner. It is obvious that a jtorch or any other convement ignition device 1 may be used without deviating from the spirit of 1 this invention.

Liquid fuel under pressureenters the barrel 8' of the atomizing nozzle I through' pipe ll.

orifices 8 located at the lowest part of the chamber. The issuing liquid fuel is ignited by the spark plug III or by any of several suitable ignition devices heretofore mentioned as it drips into the space provided between the lower extremities of the'chamber and the inside wall of the j air duct; The ignited fuel burns in the space surrounding the rearward part of the vaporizing chamber, therebyheatin'g the walls of the said I chamber. As the walls of the vaporizing chamj her are heated the fuel issuing from the orifices 1-8 is gradually: changed to vapor form. The velocity of the air stream passing through duct 9 is increased as the rate of vaporization of the fuel increases. As thehigh velocity air stream flows over the edegs of flanges 3 and 4 eddies'are created on the downstream side of the flanges which a help the rapid mixing of the air and the fuel vapors issuing from orifices 8 for burning. The

presence of the flanges 3 and 4 provides a sheltered zone in the air stream adjacent to the rearward walls of the vaporizing chamber where j.

the mixture of air and fuel vapors ignite and the air stream, also in providing the sheltered burn with a blue flame. The rearward walls of 1 the vaporizing chamber are maintained hot by the flame surrounding the said walls. It will be 3 observed that in the absence of air inside the vaporizing chamber the fuel vapors cannot ignite inside of the said chamber; consequently, the temperatures of the walls of the chamber may be allowed to'rise to any point within the range of the temperature resistance of the metal from 3 which the chamber walls are fabricated.

higher the It will also be observed that the velocity of the air stream in the duct 9 the more are the turbulences created by the flanges 3 and .4, hence, the more rapid becomes the mixing of the fuel vapor and air which results in I more rapid combustion.

It will be observed that although in Figure 1 flanges 3 and 4 are shown in a plane perpendicular to the longitudinal axis of the vaporizing 1 chamber, many modifications in the arrangement of the said flanges or an equivalent ridge to create turbulence and to provide a sheltered zone adjacent to the fuel vapor orifices 8 are a possible and within the spirit of this invention.

It will also be observed that although in Fig. 1

base to constitute a vaporizing chamber, other shapes such as hollow pyramids, hollow spheres, 1 or a cylindrical shaped housing having a bell shaped'head upstream and a cone shaped tail downstream can be used for a vaporizing chamber without departing from the spirit of this'invention.

Figure 3 illustrates a modification in the conminimizethe of the I have showntwo' hollow cones fastened base to region in the vicinity where the fuel vapors are issued through the orifices 8.

In Figures 4 and 5 is illustrated a further modification of the rearward wall 2 of the vaporizing chamber where a multiplicity of radial fins l5 and It with their planes running parallel to the longitudinal axis of the vaporizing chamber, are cast, welded, or, otherwise fastened to the outside and inside of the wall, respectively, in intimate contact with the said wall. Heat absorbed by the outer fins l5 from burning gases is conducted to the vaporizer chamber wall and to the inner fins it where the heat is transmitted to the sprayed fuel. The extraheat thus absorbed by the. fins l5 connected to the outer surfaces of the. vaporizing chamber wall and the extra surfaces exposed by the inner fins Hi to the fuel spray increase the fuel vaporizing capacity of a chamber without unduly increasing its displacement in the air stream.

It is obvious that the use of fins attached to the wall surfaces of a vaporizingchamber may be varied to the use of only outer fins, or to the use of only inner fins, or to the use of both sets of fins without departing from the intentions of this invention.

It will be observed that, although in Figures 4 and 5 are shown solid fins attached to the outside and inside of the vaporizing chamber wall,

the same results can be accomplished by scalloping, crimping or otherwise shaping the vaporizer chamber walls rearward of the fuel vapor orifices in such a manner as to provide additional heat-absorbing surfaces outside of the walls of the vaporizer chamber, and to provide additional surfaces inside of the chamber exposed to the fuel spray, thereby increasing the vaporizing capacity of a chamber without unduly increasing its displacement in the air stream, and that such variations in the construction of the vaporizer walls of the chamber do not deviate from the intentions of this invention.

In Figures 6 and 7 is shown an arrangement of a multiplicity of vaporizing units so arranged as to constitute a burner inside of a duct ll having large cross-sectional area. Although many arrangements are possible, I have shown by way of illustration an arrangement where the fuel vaporizing chambers are arranged in concentric rows. The vaporizer chambers are .connected by means of tail pipes Hi to annular headers l9, which are connected to the fuel supply under pressure. Headers I9 also constitute a frame work which supports the entire bank of vaporizing chambers.

For initiating combustion in a multiple unit burner arrangement shown in Figures ,6 and '7,

a pilot burner may be used consisting of a suitable fuel atomiz'ing nozzle 20 mounted horizontally in the axis of a diverging duct 2|, and a suitable ignition device 22. Pipe 23 supplying the liquid zone of low-velocity air stream where the fuel spray from the atomizing nozzle fl ignites by means of the ignition device 22, and continues to burn. The flame issuing from the rearward opening of the diverging duct 2| helps to warm the walls of the adjacent row of vaporizing chambers. When fuel is turned on into the vaporizing chambers, the liquidfuel dripping out of the vapor orifices in the said chambers is ignited by the flame issuing from the pilot burner. The resulting body of the flame filling the large duct ll heats therearward walls of the entire bank of vaporizing chambers so that almost instantaneously the cycle of generating and burning fuel vapors is built throughout the entire bank of burner units.

The novel features and the operation of this device will be apparent from the foregoing description. While the device has been shown and the structure described in detail, it is obvious that this is not to be considered limited to the exact form disclosed, and that changes may be made therein within the scope of what is claimed without departing from the spirit of the invention. 1

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royaltiesthereon or therefor.

What I claim is:

1. For use in a jet propulsion device including a duct adapted to have an air stream passed therethrough; a liquid fuel vaporizer, said fuel vaporizer comprising, a casing having a streamlined outer portion with a plurality of apertures therein, said casing being adapted to be placed in said duct with the streamlined portion thereof facing downstream, means for injecting liquid fuel into said casing to be vaporized whereby said fuel may be discharged in vapor form outwardly through said apertures for ignition, and a shield member disposed on said casing adjacent said apertures and on the upstream side thereof for providing a region of reduced airvelocity and high turbulence in the vicinity of said apertures.

2-. The combination in claim 1 and further including a plurality of fin-like members upstanding from the exterior wall of said casing.

3. The combination in claim 1 and further including a plurality of fin-like members extending inwardly from the interior wall of said casing.

4. The combination in claim 1 and further including a plurality of fin-like members upstanding from the exterior surface of said casing, and a plurality of fine-like members extending inwardly from the interior surface of said casing.

5. The combination in claim 1 wherein the portion of said casing on the upstream side of said shield member is bell shaped.

6. For use in a jet propulsion device including a duct adapted to have an air stream passed therethrough; a liquid fuel vaporizer, said fuel vaporizer comprising, a casing having a streamlined outer portion with a plurality of apertures therein, said casing being adapted to be placed in said duct with the streamlined portion thereof facing downstream, means for spraying liquid fuel into said casing to be vaporized whereby said fuel may be discharged in vapor form outwardly through said apertures, and a shield member disposed on said casing adjacent said apertures and on the upstream side thereof for providing a region of reduced air velocity and high turbulence in the vicinity of said apertures.

'7. For use in a jet propulsion device including a duct adapted to have an air stream passed therethrough; a liquid fuel vaporizer, said fuel vaporizer comprising, a casing having a pointed tapered portion with a plurality ofv apertures therein, said casing beingadapted to be placed in said duct with the point of the tapered por-- tion thereof facing downstream, means for injecting liquid fuel into said casing to be vaporized whereby said fuel may be discharged in vapor form outwardly through said apertures, and a shield member disposed on said casing adjacent said apertures and on the'upstream side thereof for providing a region of reduced air velocity and high turbulence in the vicinity of said apertures.

8. For use in a jet propulsion device including a duct adapted to have an air stream passed therethrough; a liquid fuel vaporizer, said fuel vaporizer comprising, first and second conical casings, each having a flange at the base thereof, means connecting together the flange portions to form a chamber, said casings being adapted to be placed in said duct with the longitudinal axesthereof parallel to the duct axis, 'and means forinjecting liquid fuel into said chamber to be vaporized, said casing on the downstream side of said flange having apertures in the wall adjacent said flange to discharge said fuel in vapor form outwardly therethrough.

9. For use in a jet propulsion device including a duct adapted to have an air stream passed therethrough; a liquid fuel vaporizer device, said device comprising, a plurality of concentrically arranged arcuate rows of header pipes adapted to be connected to a liquid fuel supply source, a plurality of pipe stubs protruding from each said header pipe, a vaporizer casing supported upon each of said pipe stubs, each said stub terminating within the casing associated therewith, said casings each having a pointed tapered portion adapted to face downstream in said duct and provided with a plurality of apertures therein, nozzle means connected to the casing end of each pipe stub for injecting liquid fuel into each said casing to be vaporized whereby said fuel may be discharged in vapor form outwardly through said apertures, and a shield member for each said casing, said shield members being disposed on said casings adjacent said apertures and on the upstream side thereof for providing a region of reduced air velocity and high turbu-- lence in the vicinity of said apertures.

KEVORK K. NAHIGYAN. 

